Thanks Matt Sharpness seems to fall off around the edges @ F/16 onwards... i find F/11 to F/14 is where it performs best. What i find more disturbing though is the distortion @ 17mm, i haven't been able to stitch a decent panorama with an obvious horizontal line yet
Yea I think with the wide angles it is a trade off and in certain images it is more evident. I tend to shoot around f13. I have stitched with the camera at 17mm and it worked fine. When shooting to stitch you should be doing a 50% overlap not just for sharp image capture but also for any fall off issues as well. Also with wide angles watch lowering the lens down as well as you will get barreling too and this will hurt your panoramic especially on a seascape horizon.